1. Field of the Invention
This invention relates to an additive for the production of paper. More particularly, it relates to an amphoteric polymeric additive for the production of paper, which is capable of retaining in the paper a water drainage-improving action and such additives as filler and sizing agent in high yields under neutral conditions.
2. Description of the Prior Art
In recent years, the neutral paper production has come to prevail in the place of the conventional acidic paper production. The neutral paper production is advantageous in (1) improving the durability of paper, (2) decreasing the possibility of corroding machines, (3) allowing safe use of inexpensive calcium carbonate as a filler, and (4) permitting a paper producing machine to be operated in a closed system, for example.
The adoption of the neutral paper production has given rise to the problem that the drainage aid heretofore used in the acidic paper production is either effectless or effective insufficiently.
For the solution of this problem, the practice of using cationized polyacrylamides obtained by the Mannich reaction of polyacrylamides, cationized starch, homopolymers of tertiary amino group- or quaternary ammonium salt group-containing polymerizable monomers or copolymers of such polymerizable monomers with nonionic monomers, and cationic polymeric compounds such as polyvinyl amines, polyallyl amines, and polyethylene imines, for example, has been in vogue.
More recently, amphoteric polymeric compounds such as Mannich reaction products of acrylic acid-acrylamide copolymers, copolymers of tertiary amino group- or quaternary ammonium salt group-containing polymerizable monomers with acrylic acid, and Hofmann degradation products of polyacrylamides have been finding utility in this practice.
Though these cationic or amphoteric polymeric compounds are used as water permeation-improving agents and as yield-improving agents such as filler and sizing agent under neutral conditions, they have the problem that they are still short of sufficiently fulfiling their roles or they are retained ununiformly in paper.
An object of this invention, therefore, is to provide a novel additive for the production of paper.
Another object of this invention is to provide an amphoteric polymeric additive for the production of paper, which enables the water drainage improving action and such additives as filler and sizing agent to be retained in high yields in paper.
Yet another object of this invention is to provide a novel pulp composition.